Each registered Medical Scheme in South Africa has a predefined rate that they will pay for a given procedure called the Scheme Rate. Medical providers can use these a guideline but are free to charge in excess of this rate.
If your Scheme states claims will be paid at 100% of Scheme Rate, it doesn't necessarily mean the full amount will be paid.
Medical Scheme A Rate = R625
Medical Scheme B Rate = R550
Provider Charge = R600
If in the above example, both Schemes pay up to 100% of Scheme Rate, Scheme B would still leave you with a shortfall of R50 to cover out of your own pocket.